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MENTOS & SODA EXPERIMENT
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Presented by
Lisa Temcov (TemcovL@cwu.edu) & Jordan Gere (GereJ@cwu.edu)

OBJECTIVES
  • Analyze Proportional Relationships
  • Using Operations with Expressions
  • Solving problems with scale drawings/graph
  • Drawing growth inferences based on samples
  • Common Core Standards
7.RP Ratios and Proportionate Relationships
7.5P Statistics & Probability

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Mini Soda Mentos
Materials - Modified Indoor Experiment (Overflows)

  • 3 Mini empty soda pop bottles per group of 6 (1 mini per partners)
  • 3 large drinking glasses per group of 6 - soda overflow catcher (mini bottles placed inside)
  • 2-4 gallon bottles of soda pop to fill reservoirs for each experiment (diet coke recommended)
  • Mentos Mint candy tablets 1+3+5= 9 per group of 6 (Must be Mint)
  • Measuring tool in millimeters (ruler, measuring tape, yard stick)
  • Index Cards (1 per person)
  • Graph paper worksheet (individuals) Poster display for graph (group)

  • NOTE:(For Outside Experiment use gallon sodas, prepare for projectile soda,
    and have students hold string shoulder to shoulder between bottle to approximate height.)
Instructions
  • Anticipatory – Hook – Video Clip

    • Diet Coke + Mentos - Champagne
      • - This is just a fun video that would get the students really excited about the possibilities of Mentos and Soda!
      • http://youtu.be/hKoB0MHVBvM

  • Explain safety rules (no eating, flinging, etc)
    • Explain handing in worksheet today and poster display is worked on next period both for their grade.
    • Ask students to make predictions based on the video clip and their experience of what may happen.
Experiment
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  • Students place their mini- bottles inside the drinking glasses that will catch the overflow of soda.
  • Students pour soda inside their mini bottles. (See Mentos distribution below)
  • Student rolls index card and places Mentos(s) inside. Other student holds another index card underneath to hold position and release the Mentos in the soda instantaenously.
  • First partners place 1 Mentos in their bottle of soda.
  • Second partners place 3 Mentos in their bottle of soda.
  • Third partners place 5 mentos in their bottle of soda.
  • Group of 6 take turns watching each other's experiment and record overflow height results.
(Time taken is recorded for extra credit graphing results.)

Display
  • Students transfer their results from their worksheet to the table sheet.
  • Students hand in the worksheet for grading.
  • Table sheet is taken homework for each to sketch the graph to transfer on poster display.
  • Next class students complete the poster graph display.
Discussions
  • Students present their results in an informal discussion.
  • Students make conclusions from their results.
  • Students differentiate differences with other student’s experiences.
  • (Different flavor and brand of sodas will show differences.)
Assessment
  • Informal assessment is tracking students as they work in partner groups by marking completion of Experiment 1-3-5 Mentos tablets.
  • Formative assessment is collected for progress grading of the experiment worksheet. A rubric is provided.
(Students have the chance to re-do the worksheet for clarity)
  • Summative assessment is the poster display and discussion participation. (Same Rubric)

Fun Facts
How does it work?
Here's the question of the day... Why does mixing Mentos with soda produce this incredible eruption? You should know that there is considerable debate over how and why this works. While we offer the most probable explanations below, we also understand and admit that other explanations could be possible... and we welcome your thoughts.
As you probably know, soda pop is basically sugar (or diet sweetener), flavoring, water, and preservatives. The thing that makes soda bubbly is invisible carbon dioxide gas, which is pumped into bottles at the bottling factory using tons of pressure. Until you open the bottle and pour a glass of soda, the gas mostly stays suspended in the liquid and cannot expand to form more bubbles, which gases naturally do.
But there's more... If you shake the bottle and then open it, the gas is released from the protective hold of the water molecules and escapes with a whoosh, taking some of the soda along with it. What other ways can you cause the gas to escape? Just drop something into a glass of soda and notice how bubbles immediately form on the surface of the object. For example, adding salt to soda causes it to foam up because thousands of little bubbles form on the surface of each grain of salt. Many scientists, including Lee Marek, claim that the Mentos phenomenon is a physical reaction, not a chemical one.
Water molecules strongly attract each other, linking together to form a tight mesh around each bubble of carbon dioxide gas in the soda. In order to form a new bubble, or even to expand a bubble that has already formed, water molecules must push away from each other. It takes extra energy to break this "surface tension." In other words, water "resists" the expansion of bubbles in the soda.
When you drop the Mentos into the soda, the gelatin and gum arabic from the dissolving candy break the surface tension. This disrupts the water mesh, so that it takes less work to expand and form new bubbles. Each Mentos candy has thousands of tiny pits all over the surface. These tiny pits are called nucleation sites - perfect places for carbon dioxide bubbles to form. As soon as the Mentos hit the soda, bubbles form all over the surface of the candy. Couple this with the fact that the Mentos candies are heavy and sink to the bottom of the bottle and you've got a double-whammy. When all this gas is released, it literally pushes all of the liquid up and out of the bottle in an incredible soda blast. You can see a similar effect when potatoes or pasta are lowered into a pot of boiling water. The water will sometimes boil over because organic materials that leach out of the cooking potatoes or pasta disrupt the tight mesh of water molecules at the surface of the water, making it easier for bubbles and foam to form.
When a scoop of ice cream is added to root beer, the float foams over for essentially the same reason. The surface tension of the root beer is lowered by gums and proteins from the melting ice cream, and the CO2 bubbles expand and release easily, creating a beautiful foam on top.
Why should you use diet Coke or diet Pepsi? The simple answer is that diet soda just works better than regular soda. Some people speculate that it has something to do with the artificial sweetener, but the verdict is still out. More importantly, diet soda does not leave a sticky mess to have to clean up.